Another concern, particularly in marine applications.... the battery case needs to be COMPLETELY sealed from moisture. I bought a Chinese 36v 100ah battery direct from China... it was cheap, about $1300 delivered, with a 40-amp charger. It worked great for several months, then failed to charge. I decided to peel the cover off and inspect. The warranty period was over, I wasn't going to ship it back to China for evaluation, so I had nothing to lose. When I got the cover off, I found the copper plates that were used to connect the cells had corroded, and corrosion on the BMS itself. The battery had never been submerged, but in the bilge of a boat, it's certainly around moisture, but never standing water. I tested the cells, and all seemed to be fine. So, I replaced the solid copper plates with nickel plated plates (E-bay), and sent photos of the battery to the company that manufactured it. They were kind enough to recognize that water vapor had caused this damage, so they sent me a new BMS and a new top for the battery, which I was very careful to epoxy back on around the entire mating surface. It's been 2 years now, operating without a hitch. So, looking forward, if I purchased another "cheap" battery for a marine application, I would look for no options like USB ports, or cover those openings with silicone sealant or something to keep out water vapor. I'd also consider sealing around the outside where the cover mates to the bottom of the case.

Thanks for the info. It was pure serendipity, er, the algo, that had your channel pop up for the first time last night for me. I just started studying these batteries last week and have already learned some crucial information thanks to you. Information that pre-saved me money because of my ignorance. Just throwing this out there for people like me in colder climates---there are battery blankets (electric-powered) that many motorists in particularly cold winter areas of Alaska use and I'm quite certain they could be useful in preventing damage to batteries in a chilly battery charging situation. Cheers!

Thanks for making this video and sharing your knowledge, it is much appreciated. Thanks again

Thanks for the review, looking to go lithium in my boat this helps a lot.

You made up my mind on what type of batteries to install in my RV. Was thinking about lipos, but we'll be in cold climates sometimes. I'll stick with lead acid for now. We don't boon dock much. But we're seriously thinking about chasing the warm weather. Then they'll be great. Excellent video.

Great video, and info. Im upgrading to Lithium from lead acid on my sailboat, and have been searching for something in the "middle of the ground " type deal, and now I have something else to further research. I have watched some of your other videos, and definitely will subscribe. Thanks.

Great post Clark. I appreciate all the information you are sharing here. I always enjoy tuning into your newest post. 💛 🌴⛵️🌞

Great job Clark, love how you think. I see the comments about buying much more expensive batteries and I get it. If you were crossing oceans or backing up something critical, I would agree, but spending good money on a temporary situation is extravagant.

Thank you Clark for this happy and positive video :-) This video has reminded me to check the charging on my sealed lead acid battery for my HF radio. It'll almost be done. But now I am off to water the baby lettuce. Cheers :-)

Love your work, Clark!

Thanks for the link. It will be a while before I install the electrical system in my C-25 bare hull refit. These look like what I need to get ready for sea trials.

I discovered your channel this morning. I've been following a few of the better known sailing channels for the last 2 to 3 years. I am surprised that I haven't come across yours until now. I think the tie-in was the LiFEP04 battery review. I also build my own battery backup systems. Great video. I appreciated your take on the grading of batteries. It is an interesting viewpoint to consider. You are not right or wrong. Much like many topics, it is another ambiguous topic which seems to have no valid data source to demonstrate definitive proof one way or the other. What some have said is only an opinion. Unless there is demonstrative proof, it is simply an opinion. Like many, I am also leary of the claim of low temperature protection. But you are correct in that if you don't live in a climate necessitating below freezing charging, you don't need that feature. I searched for other YTube videos that reviewed this battery. You seem to be the first. I would like to see a few more YTube reviews, preferably with a cold temp charging test before making any decision. I will definitely check out your other videos now that I have found your channel.

Thanks for the no nonsense non-tech breakdown on this battery. It looks like it might be a good candidate for when I set up my home backup.

Great video. Thanks. That's a sweet affordable turnkey solution, but as a full-time RVer I was looking to replace the 2 golf cart batteries that were located under the steps of my motorhome with the highest capacity LiFePo-4s that would fit in this limited space. We decided to build our own 560ah LiFePo-4 battery bank with a 330amp Heltec BMS (to start the 5,500-watt onboard generator) and a 5a active balancer for under $1,500. We built our 12v battery out of 8 grade "A" 280ah LiFePo-4 prismatic cells having an 8,000-cycle projected life at 80% DOD or 6,000 cycles at 100% DOD. This means that if we cycled them 100% every single day, 365 days a year, they would last over 16 years! So, they're obviously going to wear out from age before they wear out from cycling as we only use 15-20% of their capacity daily giving us enough reserve capacity for several days of bad weather before we have to run our generator for charging. They even saved us 35 lbs compared to our old FLA batteries and have over 5 times their capacity. Of course, it's not just a drop in like the pre-assembled PUPVWMHB battery you featured. We top balanced the cells before we assembled the battery, though they were all within a tenth of a volt when we received them. This was probably unnecessary as our 5-amp active balancer would have surely done the job, but spending this much money, we wanted to do the job right. They were economical too. $1,500/560ah = $2.68/ah vs $299/100ah = $2.99/ah for the PUPVWMHB battery. There are cheaper "B" cells available from China that are typically rated at 3,500-4,000 cycles, but we decided to spend a little more to get the higher rated cells shipped from a California warehouse, so if we got a bad one it would be easier and quicker to return and get a replacement. Happily, this wasn't necessary. We insulated the battery compartment, cut a 1" hole in our step risers and installed a tiny computer CPU fan to circulate just enough room temperature air into his compartment keep this space at close to room temperature, so we don't have to worry about the BMS shutting down charging if they get too cold - or their life reduced from getting too hot.

Thanks for reassuring me, I bought 2 "cheap ones" from Amazon too, 180 AH each. I'll hook them up to my BBMS in the next months and will report, how they worked for me. They claim to be automotive grade as well and now I know what that means.

I’m hoping to be building a system later this your, and this episode has allayed some of my concerns. Thank you so much

As someone whose been researching the market for new batteries, my response is "Great, yet another manufacturer I need to check out!" Just kidding, of course. Seriously, I think the folks building these come up with new company names weekly. Not sure if it is intended to confuse the market, or is just a mad scramble to get market dominance before the other guy, but it does create challenges if you want to find good quality, with the features you want, at a reasonable price. Thanks again for another informative video!

For my hybrid car, a 36 to 50Ah battery works just fine,and is cheaper. I do run a 2 way diode to lower the voltage by approx 0.6V, because the 14.4 charge voltage triggers the bms fron charging it (I think the car charger sends 15V pulses to determine how full the battery is, shutting down the bms). The diodes are like up to 1200v or something, some people ran them with 180A peak, 50+A continuous.

I stand corrected- only this battery seems to be $254- compared to the brands i was looking at before which have skyrocketed in price- just not sure about the quality of this particular brand- but certainly a great price!!! Thanks for sharing.

I enjoyed that as a “ nontech “ and limited funds person, thank you . And for those that have to have all the I s dotted and the T s crossed tested to the Nth degree destruction and 110 % guarantees, just buy the big dollar version and don’t bother watching. Cheers Clark .

I converted my water well to off grid solar. 400 watts plus I added 4 lead acid deep cycle marine batteries and a back up 110 ac plug in if I drain the batteries during an irrigation cycle at night. At the time all I could afford was the lead acid batteries. They have served me well for three years. Two failed under warranty within the first year but all is good now. I'm getting ready to replace these abd go to li-po. Thanks for the video. My batteries are in a large insulated box shaded by the solar panels with a small computer fan to vent it.

Excellent lesson! TY.

This is awesome information!!!! Dope video !!!!

I really enjoyed your thoughts and approach to this review 👍 Thank you for this. I have been watching UKposts videos and trying to figure out if this battery could be a drop in replacement for the lead acid battery on my travel trailer. It's just the stock configuration. 2020 Forest River Wildwood. I am a nurse and I don't know anything about battery systems and have gotten so much confusing information when looking into this.

Hello Clark - thank you for all of your insight. I plan to purchase this battery from your online store as my first LiFePO4 experience, however I would like to confirm that the battery will work well in the way that I am planning to use it on my boat. I have a portable refrigerator which will draw 30W or less depending on how cold I want to operate it. I have a smart battery charger (120V shore power) which works for LiFePO4 batteries and I have a solar panel which is rated for 50W which also has a PWM style controller. The LiFePO4 battery has a BMS to protect against overcharging, etc. and I would like to connect my smart charger to the LiFePO4 battery during the weekdays and when I use the boat for a weekend trip (2-3 days max) I want disconnect the smart charger and then connect the solar panel to the LiFePO4 battery so it can keep up with the demand of the refrigerator until I return to the dock and switch back to my smart battery charger plugged into shore power. So at this time I only want the LiFePO4 battery to have a singe use which is to run the portable refrigerator when I am away from the dock. What do you think? I actually have two additional smaller 7W solar panels which I use to keep my lead-acid batteries (2) topped off all the time. My lead-acid batteries power the engine starter and all other normal lighting/pump functions on the boat. Later I may consider joining the LiFePO4 battery with the lead-acid with your Battery Manager, but for now I want to keep it simple until. Thank you in advance for your comments and suggestions. Keep up the great work!

Best sailing nerd on the internet, thank you. I am looking to purchase a new battery in the spring, so great info.

Great video, quite insightful. We moved completely off-grid in 2019 and originally used 16-Lead/Acid 6v 232ah batteries to power our system. They worked well until they got cold in Winter. This past May we upgraded our Battery Bank to LiFePO4 We went with 4 Powerqueen Batteries. The 12.8v 300ah (200Amp BMS) units and got em delivered to the cabin from Amazon for $1000/ea. They have been a huge power upgrade, haven't given us a lick of trouble and have seriously put a damper on our generator usage as we can go several days without sun now without running the batteries dead. These Lithium's deliver a ton more power in cold temps ie 35F-40F than Lead/Acid EVER could! Lithium for Life out here! 🤠

Very helpful! Thx!

Hey there, thanks for sharing your honest review bout' Chinese Lithium Ion Battery. I too am a BIG user of Chinese Lithium Ion Battery which I purchased (Amazon) almost over a year ago. I used Renogy DC-DC 50a charger to manage the charging from source power alternator/solar panel. Eversince, never had an issue with the Battery, and it always stays up to 100% charge when it picks enough 🌞. I have my 75L Fridge stays ON at all times, charge 3 Cell Phones (now & then), sometimes use the Sirocco II Fan (Day or Night), Hard Korr LED lights. When I used all these loads at night, by midnight I checked my Battery left Charge Capacity is between 95%-100%. But when I add the load to charge DJI Mavic 2 Drone 3 Batts at the same time, I still have 80%-85% Battery Charge left. So, it really depends on how I use, and to making SURE that the 12V DC system is well capable to handle the application. So, my point is that Chinese Lithium Ion Battery to me is by far exceeds my expectations, and hoping to last me longer depends on how it's being used/managed. Thank you and have a wonderful 🦃 Day!

Thank you for your videos. I am always searching for answers and information. I have a Hunter 34’6 sailboat. My goal is to completely redo and upgrade all of the electrical system including the wiring, batteries and adding solar panels. The goal is to allow me to take it out away from shore power for as long as I desire. I wish I could find an expert on these matters that would like to take a boat and design such a system. I just don’t know enough to do it myself. I am a go getter at 70 but lack the new modern information that I need

Hi Clark, thanks for your review and sharing your knowledge. A tip I got from my landlord when I was a lot younger was not to wear metal jewelery when dealing with electrics. He used to work for a mechanic whose metal watch band shorted a lead acid battery while working on the car. That was not a pretty sight... Greetz, Catran.

I bought the 100ah 12v lithium battery from dhgate the battery came in a black box with no labels no paper work but the battery seems to be a good battery i use it on my trolling motor !

I live in a skoolie and I love the idea of a bank of batteries with lead acid and lithium batteries together then plotting the curve and seeing if the two give off a better power output.

I am in cold temperatures in vemont but think I'll try 8 of them in my boat. And only charge them when its atleast 40F in the cabin. I probably wouldn't try to charge in the winter unless OAT is 40F also when on the hard.

You are evidently doing a good job pushing these items. When I click on the link (even using a VPN) they are "currently unavailable". Look great though, thanks for sharing great tips.

I needed to add a trolling motor to my kayak. A 12 pound 50 AH battery is plenty. I bought a Eco-Worthy for $135. Compared to a $100 deep cycle lead battery at 65 pounds and 90 AH theres no contest for my use. It will troll longer than I want to be on the water and get me there and back. If it lasts even 3 seasons thats better than the typical lead battery

Its called timeusb and yes these are grate. I've been testing these and can pull 150amps or even more with one 100ah battery and these are grade A cells i even shorted it out, It turned off and only way to get it back on was to give it 13 volts and back on and running fine now for 3 months. It's really a 104ah. 280 bucks new it's the pro version

I like your review and will purchase one through Amazon to have for a power backup for my PC and TV. I also purchased a Noko Genius1 battery maintainer to use on it. You mentioned something in the review that gives me second thoughts. Is this a good product to use or should I choose another way to charge and maintain this battery ? And, is it OKAY to have the battery trickle charging under a light load ?

Clark, thanks for posting. Question, to run a LiPO4 in my camper (Forest River Minilite) do I need to defeat/disable the onboard charging system..? currently running orig. flooded 2x6v setup.. thanks, Paul.

I was not aware of the problems of low-temperature charging. I saw some unscientific/unverified videos during our recent cold temperatures of Telsas not charging and "Stuck" on the "Battery Warming" cycle. They must have the same type of protection and a warmer that could not handle the artic temps?

Skip to the 5 min mark. Trust me.

Sounds good.

$300 is a pretty common price point for 100Ah LiFePO batteries now (January 2023). You can buy a LiTime, Power Queen, Redodo or Chins with free shipping for that price. All are well thought of and have good build quality as demonstrated by many documented tear downs. None of those batteries have low temperature charging cut off, but you don't really need that. Just buy a Victron charge controller with the battery temperature sense, or link it to a Victron shunt with a temperature sensor, and program it to stop charging at whatever temperature you like. You can get 100 Ah batteries with real low temp charging cut off and internal heaters for about $400-$450. Also the term "automotive grade cells" is standard marketing for LiFePO4 batteries.

Good information 😊

So happy to find this channel. Really liked this video. I would like to ask a question and would love your expert opinion. I now use 2 100AH Die Hard Marine Batteries. I always run out of juice when I am on the river in my inflatable sea eagle raft with a 34 pound thrust trolling made my Water Snake. I think it is 36 volts. My Batts are 2 years old and in bad shape, I think because I have to run them down to nothing in order to made it to the end of my boating route. I am nature photographer and videographer. Do you think this Batt will do as well or better then my 2 12v lead acid batteries. I down daisy chain them I just switch when one runs out. This deal is so good. I'm thinking of going for it. Possible 2. Thank you.

The cold temperature cut off on that battery protects it from discharging below its minimum discharge temperature it's not meant to protect it while charging.

I'm not an EE or a techy person, but I did enjoy the video. I have a 6-seat golf cart running at 48V using 8-6V FLA batteries (Trojan T-105). Would these batteries work for me? I'm in Atlanta, GA so the low temp issue shouldn't be a problem. I get good range with these 8 batteries, how would four of these compare running in series?

VW tesla and al ev cars are made to go in Skandinavia. Up to negative 30 40 degrese celsius

I appreciate your information. I am so confused as to what to do. I am running two lead acid marine deep cycle batteries as shore power in my van. They say they are 115 ah. I charge them from my alternator. I really want to upgrade to to lithium, but I’m nervous as to what I need to make this jump. Btw I currently only run lights and a 12volt fridge.

Which one is good for a trolling motor, 55lb thrust? any ideas would really help us out? Thank You.

Great video but just missing what I needed. My question I was hoping was answered was can I use this in a UPS? If yes then what would I need to do if replacing a LA, if not can you recommend one for such an application.

Great info as per normal

Thank you!

I loved the video and happy you shared your experience and knowledge. I didn't understand the part where you talked about your battery manager ? After touring your Bank Manager site, it seems that product is for charging different types of battery's together ? But, I will only have the one lithium battery you speak of in this video and only small amp draw during day fishing trips infrequently. (every other week-end for the summer in Louisiana) I'm looking for a recommendation on a correct charger for this battery and how to manage the charging for maximum life. (i.e. leave it charger ? disconnect when full ? charge after fully drained ? or, charge each time it's used even if not drained ?) Thank you for your generous consideration, Sincerely .........................

what some systems will use is a heater near lithium batteries. I am still learning about this. But cold storage will use lithium, they are just set up with heaters. Haven't had any calls on it as far as I am aware of after almost 2 years of install.

Fascinating.

Pretty much the determining factor for what meets Automotive customer specs is Internal Resistance followed by Watt Hours/Average Voltage. Every customer is going to have different requirements but at its core what matters is voltage drop and the cells ability to discharge that power at a certain C rating. For the large prismatic LiFeP04 cells that is almost alwasy 1C continuous/2C burst. Part of the bonus of having low IR is that you'll have less voltage drop meaning you'll have a higher voltage throughout the discharge giving you a higher Wh figure and higher average voltage. The automotive grade cells seem to have an extra margin built into them, they'll test at least 5% higher in Ah, sometimes as much as 10% higher, and their internal resistance will be 75% of the "typical" rating on the datasheet. This is why we can get Grade B cells that meet capacity in Ah (but often fall a bit short on Wh) and exhibit acceptable voltage drop under large loads due to an IR that is somewhere close to spec, maybe just above the typical rating.

Hello Clark, great job, I want to put this battery in a 13-foot Jon Boat to run a Minn Kota 50 lb thrust trolling motor, is this a good choice to do the job? Please let me know what you think.

Excellent video. Thank you!

Hi Clark, thx for the information, ? I have are these batteries able to start diesel engines because they need more amps to start. Thx

Interested in lithium but a lot of study required for me to get sufficient know how! Thanks, SkipRay.

I see on your shopping area you have a trolling motor. I have a 7ft fiberglass trihull dinghy. Whats your oppion on this battery and the 12v 55lb thrust trolling motor.

Looking to buy an electric outboard motor for a small boat. The one I’ve looked at requires a 48V100A/3- battery. At times the boat will be used in sub freezing temperatures. The outboard motor is rated at 1200 watts max. Noted one of the other comments below was from someone that the battery failed due to moisture. Could the battery be put into a water proof container ( a sealed ice chest?) to help with moisture issues? And what would you look for in a battery for this type of application. Thanks in advance for any input.

Thanks for this video. I'm about to become a nomad and this battery is the right price.

Always appreciate non paid unbiased review! Thank you! Sadly amazon link shows as unavailable :(

I'm getting a 2023 motor coach. It has 1 200 watt solar panel, a 1000 watt inverter , a dual controller what ever that is and 2 100 AH AGM batteries. I plan to up grade the inverter to 2000 or 3000 but initially would like to upgrade to a 200 or 300 AH lithium battery, can I just drop a lithium in with my current equipment ?

Would you recommend these for use in a boat for the trolling motor? I have 12v on one boat and also a 36v trolling motor on another.

Batteries are charged at a voltage that will cause a rate of gassing that will break up sulfates (or probably phosphates for PO4 batteries). That voltage varies depending on the temperature of the battery. If the temperature gets too low, the charge will not produce the gassing that is required to keep the battery healthy. The temperature is not a factor when discharging the battery. Since the charger does not know the temperature of the battery, it probably just senses its own temperature to determine the correct initial charge voltage. Therefore, you will get the best life from your battery if the charger and the battery are in the same area, at the same temperature. Also, if the battery is hot (from a long heavy discharge), let it cool off to room temperature before you charge it. Just some tips from an old Sub sailor that had to maintain some very large lead-acid batteries.

wow I know that opening theme song - learned it traveling around the country last year on fiddle Big Siota

I'm considering replacing a traditional lead acid battery with Li ones for a gate motor. The lead acid ones come at 12V 7.2Ah, and I would like to replace that with an Li one at 12V, 8Ah. The form factors are exactly the same with similar charging and discharging characteristics. Do you think this would be a good idea? Can the Li cells withstand the outdoor heat of up to 35 degC but it sits inside a box of course. Also, will the charging circuit that came with the lead acid battery also work on the Li ones? I appreciate your honest opinion and thanks!

Can you add those batteries in series and what is the maximum voltage and amps it will support before the BMS shutdown the charge and discharge, thanks

The advertisement for this battery suggest use for RV. Does this mean this could replace the existing 12v lead acid directly or does it require a dedicated charge manager? I'm guessing the onboard BMS could do the job but I'm not sure if this is the case. Plus, my RV does not have a solar so I'm planning to add solar while replacing the existing lead acid bank.

Amazon battery is 1/3 the cost of Battle Born battery, which is a no-brainer. Will Prowse open a lot of these batteries and recommend them. If you are handy, you can build it with selected cells even better. With power and a computer fan, cold weather is fine. That beats water drying up in a lead-acid battery any time.

Great review ...as always. Also, like your delivery. I race single handed on 320 mile races. I have 3 agm and a 100 watt solar panel. I have would like to save weight and not use the engine to recharge as often, so this sounds helpful. BTW, I use about 3.5 amps per hour. Thanks

nice review, so what about integrating a 20A 14.6V AC-DC charger to 12.6V 20Ah battery bank(3), using +/- busbars connected to a 30A PV controller? The charger operates at the exact maximum of the batters parameters, thinking about buying a 5-10A charger for this battery bank and saving the 20A charger for more expensive 50-100Ah LiFe batteries.

I so appreciate your review, im just lost if I can use this as a 2nd amp in my car audio...there's so many little nuances when it comes to batteries

I plan to replace my 2018 4Runner OEM battery with AGM Yellow Top Optima battery. At this price point should I get this lithium battery? Will this battery work with my 170w solar panel and Renogy controller? The solar panel charges my ARB fridge, Bluetti power station, and top off my battery. Thanks

I got 2 of the generic orange batteries with black tops. They were 100Ah with 100A BMS and get this, Bluetooth monitoring!! Oh the 2x cells were delivered for $550 total!!! These seem bad ass. I just got them so I'm not sure of anything yet but I think I got the best deal but I used eBay. These are brand new. Seller had 99.9 seller rating.

Omg you are probably the perfect person to ask! I have an inflatable boat with a sailing rig and take it on a really small lake. I want to add a small trolling motor (30 pounds) just to go a very short distance back if my daughter doesn’t want to row. These inflatables don’t sail well at various points of sail. They slide! So i would go no more than 30 minutes because the whole point is sailing. What’s the lowest power lifepo4 cheap battery i can use for this? The one you described is too expensive. Thank you so much!

I wonder if this can work on a car. Setting the car to think it has a AGM battery onboard it will charge it at 14.7-14.8V ... will it work?

Welcome I have two lithium batteries, each one 12 volts, 150 amps connected to System 24 Why does the first battery charge before the second battery when it only works for two hours? The draw from the two batteries is only one amp..?

living in quebec Canada winter time is cold i think it could be a problem if a power out lasted more than a day temperature could i mean potentially coul freeze does not happen often but.? better safe than sorry. i would go for a self heating battery .I know they are expensive :( but a safer decision ? have to save for that expensive self heating one. I appreciate your video .BUT maybe at that price i could try one and also buy one expensive one in case. keep up your good information videos.

Great vid. Using Ur link to Amazon this battery is now $170, amazoning price. I am ready to buy one. U failed to mention charging, but seemed to say a regular 12v charger will not produce enough volts????

Bummer, I live in a cold climate, Wisconsin, so I would need to move these to the inside of the trailer, I can't leave them on the outside in the battery box, if cold outside I cant heat it until spring. :) I didn't hear you say that it had an built in heater, hoes it? Thank you.

When using your BBMS. Could you use it to split 2 banks of LiFePo2 batteries of different brands and purchased at different times?

The damn things catch fire! Phooey!

Clark which battery should I buy for a 24v trolling motor for my boat it’s a 80lb thrust Thanks

I have a question. If I have intentions of getting four batteries to hook up inlune what size solar panels do I need to keep them going? Does this even make sense?

Thanks Clark. Hi to Emily. I would assume that the battery was designed for automotive use, A or B were still designed for auto. I do like the idea of trying the cheapest. I usually buy the cheapest tool or the top of the line..... Someone could build their own freezing temp cut off, right? I watch Will Prowse and he finds temp probes that are not connected to the battery, when doing his destructive tests.

how did you work out the total amps that it give out at the end, like you said the battery is 108A? I brought a solar deep cycle battery and the guy said they 100ah but i got a feeling it less.

Do these lithium batteries work without solar? What components in my trailer (not RV) would I need to change to make it work with a generator for charging?

Thanks! I keep not purchasing any for my indecision on unknown brands. Despite my lead being intolerable. Plenty of 'recommendations' from those getting them for free and paid. There is a good call on insulation of the battery bank with heating mat. Just ventilation or cooling for high temperature. An engine cooling loop ( exchanger based) on a thermostatic controlled pump is simply to heating. While my boat has had winters at anchor unoccupied self heating, lithium iron phosphate has not been a perfect choice. Rather like an auto run testing bilge pump, it can just consume power without replacement. Despite the starting battery form factor, I assume this is not a starting battery?

What about using a 12v battery heater to maintain the battery temperature during charging in cold temps?

This is what I'm trying to find out because if you're on solar charging in the winter time and it's 40 belleau and your battery is equivalent to that temperature. To charge it by solar energy is going to ruin that battery?

Eco-worthy gel battery 100ah trying to get to as secondary batteries but still gonna charge it off alt will that be ok

yeah you should, unless you like expensive decals from BB..Weize on sale now for 100ah $254.79 been using for over 1 yr. more on order as of yesterday. 10 yr warranty.

3:58 40A discharge rate ? That's gotta be at a fairly low voltage, because AFAIK a very modest max discharge rate is pretty much THE defining limitation of LIFEPO4 tech in general. Am I off or on target ?

Many folks are confusing "low temp cutoff" with "low temp CHARGE protection" and they are very different. Low temp cutoff, low temp protection, etc. only protect the battery during discharge. These sellers use "low temp cutoff", "low temp protection" (or something similar) to make you think their battery has low temp charge protection when if fact most do not. To be clear, nowhere in the specs for this battery does it state it has "low temp CHARGE protection", it only states low temp protection and that will not cut charging below freezing. This battery does NOT have low temp CHARGE protection so do not charge it below freezing.

Actually running the microwave is something we do. 1500 watts for 3 minutes. Should try that.

I know enough batteries to know the LiFePo4 is 3.6v fully charged when new, 4 batteries in series equals 14.4v, it should be discharged to 3.2v, 4 = 12.8v. If 12.8v is the discharge cut off voltage then the batteries are either new balanced or one has greater or lower voltage to make 12.8v. Automotive quality must all have the same voltage +/- 0.01 to 0.02v to be balanced. Check the voltage with a meter when discharged and full to see if they are second hand or not balanced when full.